Heretofore, a large number of cleaning agents suitable for cleaning surface of hard articles such as bathroom tiles and toilet seats in a house have been developed and reported. Among these cleaning agents, in view of cleaning efficiency and safety in use, hard article surface cleaning agents acidified with an organic acid have been attracted much attention. As technologies on the cleaning agents, there are reported a combined use of an organic acid and sodium salt of an organic acid (JP-A-53-94309), a combined use of a hydroxy carboxylic acid and a surfactant (JP-A-55-147600), solidification of constituents of a hydroxy carboxylic acid etc. (JP-B-7-116479), and an acidic microemulsion containing a hydroxy carboxylic acid (JP-A-7-305100, EP 630963 A2). These technologies focuses on cleaning function how to remove stains and purposes to enhance cleaning power. Each of the publications contains a description of possible combined use of a fragrant material in the cleaning agent but no precise investigation has been made on the fragrant material to be used and detail of the fragrant material has not been described. JP-A-7-305100 only discloses that α-terpineol is suitable as the fragrant material but the compound is only described as suitable but is not investigated in detail, still less the other fragrant materials.
Recently, with regard to cleaning liquids, a product which has not only a high cleaning power but also is scented with fragrance pleasant to consumers has been required. In particular, for a product used in the house, it is strongly requested that a pleasant fragrance is maintained over a long period of time. However, the request cannot be satisfied even if a fragrant material be only added and mixed in the cleaning liquid for satisfying the request. The reason is mainly as follows. That is, many of fragrant materials are compounds having an ester group or an aldehyde group and in the case of a long-term storage of strongly acidic aqueous solution or dispersion of the fragrant materials, there is a possibility that the fragrant materials are hydrolyzed or oxidized during the storage. In particular, in the case of a long-term storage of strongly acidic aqueous solution or dispersion containing the fragrant compounds, there is a risk of deterioration of initial quality, e.g., change in appearance of the solution or dispersion, deterioration of the fragrance, or formation of precipitates.
An aqueous solution or dispersion adjusted so as to be strongly acidic with an organic acid can be widely utilized as a hard article surface cleaning agent but it is extremely important to provide a product scented with a pleasant fragrance in use. At selection of a fragrant material to be mixed, a fragrant compound or fragrant composition stable in an acidic hard article surface cleaning liquid adjusted so as to be strongly acidic, particularly to pH 2.0 to 3.0 is required.